The increasing number of cases of herpes simplex-2 (HSV-2) in the United States appears to have been reversed, with a reported decrease in the number of people with the virus in recent years. Unfortunately however, the good news doesn't stretch to herpes simplex virus type 1, which experts believe might actually be gaining ground.

HSV-2 is the virus responsible for most cases of genital herpes and is one of the most prevalent sexually transmitted infections worldwide. HSV-2's cousin, the herpes simplex 1 virus (HSV-1), is typically transmitted during childhood via nonsexual contact and is regarded as a less serious risk to health. Despite its high prevalence however, HSV-1 can also cause genital herpes. Both types of herpes can cause serious disorders such as blindness, encephalitis and neonatal infections.

The new findings, reported in the Journal of the American Medical Association, were based on data from National Health and Nutrition Examination Surveys conducted during 1976-1980, 1988-1994 and 1999-2004. While HSV-2 cases appeared to be increasing in the course of the first two surveys, there was a decrease apparent in the last periods.

Specifically, the researchers found that the prevalence of HSV-2 was 21 percent in 1988-1994 and 17 percent in 1999-2004; a significant decrease between the 2 surveys. The decrease in HSV-2 was most strongly noted in persons aged 14 to 19 years.

The researchers aren't sure why the HSV-2 decrease has come about, but speculate that it may be due to changes in sexual behaviors; including more careful partner selection, greater condom use, and/or choosing oral sex over vaginal sex.

Based on material from the Journal of the American Medical Association